JP2003300316A - Liquid ejector and its controlling method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform printing at a speed higher than that in normal mode while ensuring ejection stability of liquid drop. <P>SOLUTION: A control section controls a carriage mechanism such that the scanning speed of a carriage becomes higher in high speed mode as compared with normal mode, and controls a drive signal generating means such that the driving period becomes shorter in high speed mode as compared with normal mode. When the environmental temperature is lower than a specified level in high speed mode, the drive signal generating means is controlled to generate a drive signal which can generate an ejection pulse having such a waveform as the quantity of liquid being sucked into a pressure chamber before ejecting an ink drop increases as compared with normal time. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid ejecting apparatus capable of ejecting a plurality of droplets per pixel and a control method for the apparatus.

[0002]

2. Description of the Related Art An ink jet type recording apparatus, which is an example of a liquid ejecting apparatus, has a recording head having a large number of nozzle openings formed in a line, and the recording heads in a main scanning direction (recording paper width direction). And a paper feed mechanism for moving the recording paper in the sub-scanning direction (paper feed direction).

The recording head described above includes a pressure chamber communicating with the nozzle opening and a pressure generating element for changing the ink pressure in the pressure chamber. In this recording head, the ejection pulse is supplied to the pressure generating element to change the ink pressure in the pressure chamber to eject the ink droplet from the nozzle opening.

While moving in the main scanning direction, the recording head
Ink droplets are ejected at the timing defined by the dot pattern data. When the recording head reaches the end of the moving range, the paper feeding mechanism moves the recording paper in the sub scanning direction. When the recording paper is moved, the carriage mechanism moves the recording head again in the main scanning direction, and the recording head ejects ink droplets during the movement.

By repeating the above operation, an image based on the dot pattern data is recorded on the recording paper.

This recording device forms an image depending on whether or not ink droplets are ejected, that is, the presence or absence of dots. There is a type of recording apparatus of this type in which a plurality of ink droplets can be ejected to one pixel and the gradation is adjusted by changing the number of ejections per pixel.

By the way, there is a case where not so high image quality is required depending on the printing application. In such a case, there is known a technique for reducing the number of ink droplets ejected per pixel to suppress the ink consumption. There is. That is, the ink consumption is suppressed in exchange for the deterioration of the image quality.

[0008]

However, with the above-described technique in which the number of ink droplets ejected per pixel is thinned, the printing speed is the same as in the normal mode.

Generally, in order to increase the printing speed, it is conceivable to increase the scanning speed of the carriage and to shorten the ink ejection interval between pixels, that is, the cycle of the drive signal (drive cycle) accordingly.

However, by shortening the driving cycle, the flow velocity of the ink in the ink flow passage formed in the recording head becomes faster, and accordingly, the ink flow passage is formed to control the ink flow amount. The flow resistance of the ink at the ink supply port increases. This phenomenon is
This is remarkable in a so-called multi-shot type device that ejects a plurality of ink droplets per pixel in the same drive cycle, and there is a risk that the ejection stability of the ink droplets may be impaired due to an increase in flow resistance. In addition, this phenomenon remarkably appears when the environmental temperature is low and the ink viscosity is high.

The present invention has been made in consideration of the above circumstances, and has a high-speed mode capable of printing at a higher speed than in the normal mode while ensuring the ejection stability of droplets. An object of the present invention is to provide an apparatus and a control method for the apparatus.

[0012]

In order to solve the above problems, the liquid ejecting apparatus according to the present invention applies a discharge pulse to a pressure generating element provided corresponding to a pressure chamber communicating with a nozzle opening. A recording head configured to generate pressure fluctuations in the liquid in the pressure chamber to eject liquid droplets from the nozzle opening; and a carriage on which the recording head is mounted, and the recording head is scanned in the main scanning direction together with the carriage. A carriage mechanism for driving the drive mechanism; drive signal generating means for generating a drive signal capable of generating a plurality of the ejection pulses per drive cycle in order to eject a plurality of liquid droplets per pixel; Pulse generation means for generating one or more ejection pulses by selecting a part or all of them, a normal mode for printing at a normal speed, and the normal speed A control means for controlling the drive signal generating means and the carriage mechanism according to a switching operation to a high speed mode for printing at an even faster speed, the control means in the high speed mode than in the normal mode. Also controls the carriage mechanism so that the scanning speed of the carriage becomes faster, and controls the drive signal generating means so that the drive cycle becomes shorter in the high speed mode than in the normal mode, and When the ambient temperature is lower than the predetermined temperature in the high speed mode, the drive signal generating means is controlled to generate a waveform such that the amount of liquid sucked into the pressure chamber prior to the droplet discharge becomes larger than that in the normal time. The driving signal capable of generating the ejection pulse is generated.

In order to solve the above-mentioned problems, the present invention applies a discharge pulse to a pressure generating element provided corresponding to a pressure chamber communicating with a nozzle opening, thereby causing a pressure fluctuation in a liquid in the pressure chamber. A recording head for generating and ejecting droplets from the nozzle opening, a carriage having the recording head mounted thereon, and a carriage mechanism for scanning the recording head together with the carriage in the main scanning direction; Drive signal generating means for generating a drive signal capable of generating a plurality of ejection pulses per drive cycle in order to enable the ejection of the liquid droplets, and selecting a part or all of the drive signals from the drive signal. Pulse generation means for generating one or a plurality of the ejection pulses, a normal mode for printing at a normal speed, and a high speed mode for printing at a speed faster than the normal speed And control means for controlling said drive signal generating means and the carriage mechanism in accordance with the switching operation,
In the method of controlling a liquid ejecting apparatus, the carriage mechanism is controlled so that the scanning speed of the carriage is higher in the high speed mode than in the normal mode, and in the high speed mode compared to the normal mode. Also, the drive signal generating means is controlled so that the drive cycle is shortened, and when the environmental temperature is lower than a predetermined temperature in the high speed mode, the drive signal generating means is controlled to discharge liquid droplets. The drive signal capable of generating the ejection pulse having a waveform such that the amount of liquid sucked into the pressure chamber is larger than that in the normal state is generated.

Preferably, the drive signal generating means is controlled so as to generate the drive signal in which the number of droplets ejected per pixel is smaller in the high speed mode than in the normal mode.

Further, preferably, the allowable range of the environmental temperature in the high speed mode is set narrower than that in the normal mode.

Further, preferably, the allowable range of the environmental temperature in the normal mode is about 10 ° C. to about 43 ° C., and the allowable range of the environmental temperature in the high speed mode is about 15 ° C. to about 35 ° C.

Further, preferably, the pressure generating element is constituted by a flexural vibration mode piezoelectric vibrator.

Preferably, the pressure generating element is composed of a longitudinal vibration mode piezoelectric vibrator.

[0019]

DETAILED DESCRIPTION OF THE INVENTION An ink jet recording apparatus as an embodiment of a liquid ejecting apparatus according to the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view showing a schematic structure of the ink jet recording apparatus according to this embodiment. In FIG. 1, reference numeral 1 is a carriage, and the carriage 1 is configured to be reciprocally moved in the axial direction of the platen 5 while being guided by a guide member 4 via a timing belt 3 driven by a carriage motor 2. There is. The carriage 1, the carriage motor 2, the timing belt 3, and the guide member 4 form a carriage mechanism that causes the inkjet recording head 12 to scan together with the carriage 1 in the main scanning direction.

The ink jet recording head 12 is mounted on the side of the carriage 1 facing the recording paper 6, and an ink cartridge 7 for supplying ink to the recording head 12 is detachably mounted on the upper side thereof.

A cap member 13 is arranged at a home position (right side in FIG. 1) which is a non-printing area of the ink jet type recording apparatus. The cap member 13 has a recording head mounted on the carriage 1 at the home position. When moved, it is pressed against the nozzle forming surface of the recording head to form a closed space with the nozzle forming surface. Further, below the cap member 13, a pump unit 10 for applying a negative pressure to the closed space formed by the cap member 13 is arranged.

In the vicinity of the printing area side of the cap member 13, a wiping means 11 having an elastic plate such as rubber is provided.
Is arranged so as to be able to advance and retreat in the horizontal direction with respect to the movement trajectory of the recording head, and when the carriage 1 reciprocates toward the cap member 13 side, the nozzle forming surface of the recording head can be wiped as necessary. It is configured to be able to.

The ink jet recording apparatus according to the present embodiment further comprises a feeding mechanism for intermittently conveying the recording paper 6 on which recording is performed by the recording head 12 in the sub scanning direction orthogonal to the main scanning direction. .

FIG. 3 shows the structure of the recording head of the ink jet recording apparatus according to this embodiment.

The recording head 12 includes a plurality of pressure chambers 31.
Actuator unit 32 in which a nozzle opening 47 and a common ink chamber 33 are formed in a flow path unit 34.
And a piezoelectric vibrator 25. The flow path unit 34 is joined to the front surface of the actuator unit 32, and the piezoelectric vibrator 25 is arranged on the back surface of the actuator unit 32.

The pressure chamber 31 expands and contracts as the piezoelectric vibrator 25 deforms, and changes the ink pressure in the pressure chamber 31. Then, an ink droplet (droplet) is ejected from the nozzle opening 47 according to the change in the ink pressure in the pressure chamber 31. For example, the pressure chamber 31 is rapidly contracted to pressurize the inside of the pressure chamber 31 and eject an ink droplet from the nozzle opening 47.

The actuator unit 32 includes the pressure chamber 3
A pressure chamber forming substrate 35 in which an empty space forming 1 is formed;
A lid member 36 joined to the front surface of the pressure chamber forming substrate 35
And a vibration plate 37 which is joined to the back surface of the pressure chamber forming substrate 35 and closes the opening surface of the empty portion. The lid member 36 is provided with a first ink flow path 38 for communicating the common ink chamber 33 and the pressure chamber 31, and a second ink flow path 39 for communicating the pressure chamber 31 and the nozzle opening 47. There is.

The flow path unit 34 is provided with an ink chamber forming substrate 41 in which an empty portion forming the common ink chamber 33 is formed and a large number of nozzle openings 47, and the ink chamber forming substrate 41 is formed.
And a supply port forming plate 43 joined to the back surface of the ink chamber forming substrate 41.

Nozzle openings 4 are formed in the ink chamber forming substrate 41.
7 is formed with a nozzle communication port 44. Also,
The supply port forming plate 43 has an ink supply port 45 that connects the common ink chamber 33 and the first ink flow path 38, and a communication port 46 that connects the nozzle communication port 44 and the second ink flow path 39. It is set up.

Therefore, the recording head 12 is formed with a series of ink flow passages from the common ink chamber 33 to the nozzle openings 47 through the pressure chambers 31.

The piezoelectric vibrator 25 is formed on the opposite side of the pressure chamber 31 with the vibration plate 37 interposed therebetween. This piezoelectric vibrator 2
Reference numeral 5 denotes a flat plate, and a lower electrode 48 is formed on the front surface of the piezoelectric vibrator 25, and an upper electrode 49 is formed on the rear surface so as to cover the piezoelectric vibrator 25.

Further, at both ends of the actuator unit 32, connection terminals 50 whose base end portions are electrically connected to the upper electrodes 49 of the respective piezoelectric vibrators 25 are formed. The tip surface of the connection terminal 50 is formed higher than the piezoelectric vibrator 25. The flexible circuit board 51 is joined to the tip end surface of the connection terminal 50, and a drive waveform is supplied to the piezoelectric vibrator 25 via the connection terminal 50 and the upper electrode 49.

Although only two pressure chambers 31, piezoelectric vibrators 25, and connection terminals 50 are shown in the figure, a large number of pressure chambers 31, piezoelectric vibrators 25, and connection terminals 50 are provided corresponding to the nozzle openings 47.

In this recording head 12, when an ejection pulse is input, a voltage difference is generated between the upper electrode 49 and the lower electrode 48. Due to this potential difference, the piezoelectric vibrator 25 contracts in the direction orthogonal to the electric field. At this time, since the lower electrode 48 side of the piezoelectric vibrator 25 joined to the vibration plate 37 does not contract but only the upper electrode 49 side contracts, the piezoelectric vibrator 25 and the vibration plate 37 project toward the pressure chamber 31 side. To bend,
The volume of the pressure chamber 31 is contracted.

When ink droplets are to be ejected from the nozzle openings 47, the pressure chamber 31 which has contracted to some extent is temporarily expanded to suck ink into the pressure chamber 31, and then the pressure chamber 31 is rapidly contracted. Let When the pressure chamber 31 is abruptly contracted, the ink pressure rises in the pressure chamber 31, and an ink droplet is ejected from the nozzle opening 47 with this pressure rise. In addition, after discharging the ink droplets, the upper electrode 4
By returning the voltage of 9 to the reference potential (intermediate potential), the interior of the contracted pressure chamber 31 expands, and the common ink chamber 33
Ink is supplied to the pressure chamber 31 from the ink supply port 45, and vibration of the meniscus is suppressed.

FIG. 4 is a functional block diagram of the ink jet recording apparatus according to this embodiment. As shown in FIG. 4, this recording apparatus includes a printer controller 61 and a print engine 62. The printer controller 61 includes an interface 63 that receives print data and the like from a host computer (not shown), a RAM 64 that stores various data, a ROM 65 that stores control routines for various data processing, and a CPU. A control unit 82 including the above, an oscillating circuit 66, a drive signal generating circuit (drive signal generating means) 83 for generating a drive signal, print data and drive signals expanded in dot pattern data (bitmap data), and the like. An interface 67 for transmitting to the print engine 62.

In addition to this, the printer controller 61 is
A card slot 7 that detachably holds a memory card 76, which is a type of recording medium, and functions as a recording medium holding unit.
7 and the information recorded in the memory card 76
Card interface 78 for sending to Data relating to the waveform of the drive signal is recorded on the memory card 76. In addition, the memory card 76
As the recording medium other than the above, for example, a floppy (registered trademark) disk, a hard disk, a magneto-optical disk, or the like can be used.

The control unit 82 is a kind of computer, and refers to the waveform data of the drive signal recorded in the memory card 76, the control routine recorded in the ROM 65, and the like to control the ejection of ink droplets.

The interface 63 receives, from the host computer, print data composed of any one of a character code, a graphic function, and image data, or a plurality of data. In addition, the interface 63 is busy with the host computer (BU
An SY) signal, an acknowledge (ACK) signal, etc. can be output.

The RAM 64 is used as a receiving buffer, an intermediate buffer, an output buffer, a work memory (not shown) and the like. Print data from the host computer is temporarily stored in the reception buffer, intermediate code data is stored in the intermediate buffer, and dot pattern data is expanded in the output buffer.

The ROM 65 stores various control routines executed by the control unit 82, font data, graphic functions and the like.

The ROM 65 stores a control routine (control program) that is continuously used without being changed. The data about the waveform of the drive signal, which is scheduled to be upgraded or changed, is recorded in the memory card 76.

The control unit 82 controls the drive signal generation circuit 83 based on the data regarding the waveform of the drive signal read from the memory card 76 to generate a predetermined drive signal described later according to the print mode.

The print engine 62 uses the recording head 12
Stepping motor 80 for driving the sheet in the main scanning direction, paper feed motor 81 for transferring the recording sheet, and recording head 162
The electric drive system 71 of FIG. Recording head 1
The electric drive system 71 of 62 includes a shift register 72, a latch circuit 73, a level shifter 74, a switch 75, a piezoelectric vibrator 161, and the like. The shift register 7
2, the latch circuit 73, the level shifter 74, and the switch 75 function as pulse generation means in the present invention.

FIG. 5 shows an example of the drive signal generation circuit 83. The drive signal generation circuit 83 includes a waveform generation circuit 91 and a current amplification circuit 92.

The waveform generation circuit 91 includes a waveform memory 93,
First waveform latch circuit 94 and second waveform latch circuit 95
And an adder 96, a digital-analog converter 97, and a voltage amplifier circuit 98.

The waveform memory 93 functions as a change amount data storage means for individually storing a plurality of types of voltage change amount data output from the control unit 82. This waveform memory 9
A first waveform latch circuit 94 is electrically connected to 3. Then, the first waveform latch circuit 94 holds the data of the voltage change amount stored in the predetermined address of the waveform memory 93 in synchronization with the first timing signal. The adder 96 outputs the output of the first waveform latch circuit 94 and the second waveform latch circuit 9
5 is input, and the second waveform latch circuit 95 is electrically connected to the output side of the adder 96.
Then, the adder 96 functions as change amount data adding means, adds output signals to each other, and outputs the added signals.

The second waveform latch circuit 95 is an output data holding means for holding the data (voltage information) output from the adder 96 in synchronization with the second timing signal. D / A
The converter 97 is electrically connected to the output side of the second waveform latch circuit 95 and converts the output signal held by the second waveform latch circuit 95 into an analog signal. Voltage amplifier circuit 9
Reference numeral 8 is electrically connected to the output side of the D / A converter 97 and amplifies the analog signal converted by the D / A converter 97 to the voltage of the drive signal.

The current amplifier circuit 92 is electrically connected to the output side of the voltage amplifier circuit 98, performs current amplification on the signal whose voltage is amplified by the voltage amplifier circuit 98, and outputs it as a drive signal (COM). .

Drive signal generation circuit 83 having the above configuration
Then, prior to the generation of the drive signal, a plurality of change amount data indicating the voltage change amount are individually stored in the storage area of the waveform memory 93. For example, the control unit 82 outputs the change amount data and the address data corresponding to the change amount data to the waveform memory 93. Then, the waveform memory 93 stores the change amount data in the storage area designated by the address data. The change amount data is composed of data containing positive / negative information (increase / decrease information), and the address data is composed of a 4-bit address signal.

When a plurality of types of change amount data are stored in the waveform memory 93 in this way, it becomes possible to generate a drive signal.

To generate the drive signal, the change amount data is set in the first waveform latch circuit 94, and the change amount data set in the first waveform latch circuit 94 is set in the second waveform latch circuit 94 at a predetermined update cycle.
This is performed by adding to the output voltage from the waveform latch circuit 95.

The control unit 82 may be, for example, a host computer directly connected to the recording device alone, or
It is also possible to use one of many computers connected via a network.

In the recording head 162 shown in FIG. 1, it is possible to control whether or not a drive signal is input to the piezoelectric vibrator 25 according to the print data. For example,
Since the switch 75 is in the connected state during the period when the print data is “1”, the drive signal (COM) changes to the piezoelectric vibrator 2
5 is supplied. Then, the piezoelectric vibrator 25 is deformed by the drive signal of the supplied portion. Further, since the switch 75 is in the non-connection state during the period when the print data is “0”, the supply of the drive signal to the piezoelectric vibrator 25 is cut off. It should be noted that during the period in which the print data is “0”, each piezoelectric vibrator 25 holds the previous charge and maintains the previous deformed state.

6 (a) and 6 (b) are diagrams showing the waveform of the drive signal generated by the drive signal generating circuit 83.
6A shows the drive signals in the normal mode and the high speed mode when the environmental temperature is 25 ° C., and FIG.
The drive signals in the normal mode and the high-speed mode in the case of ° C are shown. In FIGS. 6A and 6B, the drive signals at 25 ° C. and 15 ° C. in the normal mode are shown by the same waveform for convenience of description, but in reality, the drive signals in the drive signal are different depending on the environmental temperature. The waveform of the ejection pulse is changed. This also applies to the high speed mode.

As shown in FIGS. 6A and 6B, in this embodiment, four ejection pulses are included in the drive signal of one drive cycle T (or T '). That is, the inkjet recording apparatus according to the present embodiment can eject up to four ink droplets per pixel within the same drive cycle T (or T ′). It should be noted that it is possible to generate three or less ejection pulses and apply them to the piezoelectric vibrator 25 by selecting a part of the drive signal by the above-mentioned pulse generation means.

The control section 82 shown in FIG. 4 controls the drive signal generating circuit 83 in accordance with the switching operation between the normal mode for printing at the normal speed and the high speed mode for printing at a speed faster than the normal speed. , Fig. 6 in the normal mode
The drive signals shown by the solid lines in (a) and (b) are generated,
In the high speed mode, the drive signal indicated by the broken line in FIGS. 6A and 6B is generated.

Further, the control section 82 controls the stepping motor of the print engine 62 in accordance with the switching operation between the normal mode and the high speed mode so that the scanning speed of the carriage 1 becomes higher in the high speed mode than in the normal mode. To control the carriage mechanism.

As can be seen from FIG. 6, the drive cycle T'in the high speed mode is set shorter than the drive cycle T in the normal mode. That is, in high speed mode,
The printing speed is increased by increasing the scanning speed of the carriage 1 and simultaneously shortening the driving cycle.

Here, the shortening of the drive cycle in the high speed mode is achieved by shortening the portion corresponding to the intermediate potential (reference potential) Vm in the drive signal in the normal mode. That is, the waveforms of the four ejection pulses themselves included in the drive signal are common in the normal mode and the high speed mode.

Further, at 25 ° C. indicated by the broken line in FIG.
As can be seen by comparing the high-speed mode drive signal at 15 ° C. with the high-speed mode drive signal at 15 ° C. indicated by the broken line in FIG. 6B, the intermediate potential Vm ′ at 15 ° C. is 2
It is set higher than the intermediate potential Vm in the case of 5 ° C.
That is, when the temperature is 15 ° C. in the high speed mode, the amount of ink sucked into the pressure chamber 31 prior to ink ejection is
It becomes larger than that at 25 ° C.

Since the driving cycle T'in the high speed mode is shorter than the driving cycle T in the normal mode, the ink flow velocity at the ink supply port 45 of the recording head 12 shown in FIG. Flow resistance increases.
For this reason, if no treatment is applied, the ejection characteristics in the high-speed mode may become unstable, especially at low temperatures. However, in the present embodiment, when the high-speed mode is executed at a low temperature, the amount of ink sucked into the pressure chamber 31 prior to ink ejection is increased, so that the ejection characteristics are prevented from becoming unstable. be able to.

Further, the control unit 82 sets the allowable range of the environmental temperature in the high speed mode to be narrower than that in the normal mode. For example, when the allowable range of the environmental temperature in the normal mode is 10 ° C to 43 ° C, the allowable range of the environmental temperature in the high speed mode is set to 15 ° C to 35 ° C, and when the allowable range of the environmental temperature exceeds the allowable range, the high speed mode is set. So that you cannot select. This is because, as a result of raising the intermediate potential in the high-speed mode at the low temperature as described above, the potential difference of the damping waveform for stabilizing the meniscus after ink ejection may not be sufficiently obtained, and the temperature is too low. Considering that raising the intermediate potential may not be sufficient, and that if the temperature is too high, the ejection characteristics may become unstable due to an increase in the ink flow rate due to the shortening of the drive cycle. is there.

In the present embodiment, the maximum number of ink droplets ejected per pixel in one driving cycle is 4 in both the normal mode and the high-speed mode. However, in the high-speed mode, as shown in FIG. The last ejection pulse in the drive signal shown in (b) is omitted and the maximum is 3 per pixel.
It is also possible to set the droplets to further shorten the driving cycle T ′ and further set the scanning speed of the carriage 1.

In this way, although the image quality is lower than in the normal mode, the printing speed in the high speed mode can be further improved and the ink consumption can be suppressed.

In the above embodiment and its modification,
The recording head 12 using the flexural vibration mode piezoelectric vibrator 25 as a pressure generating element has been illustrated, but the present invention is also applicable to the recording head 162 using the longitudinal vibration mode piezoelectric vibrator 161 shown in FIG. You can

The recording head 162 includes a base 163 made of synthetic resin, and a channel unit 164 attached to the front surface of the base 163 (corresponding to the left side in the drawing).
The flow path unit 164 has a nozzle opening 165.
Nozzle plate 166 having a hole formed therein, and diaphragm 167
And a flow path forming plate 168.

The base 163 is a block-shaped member provided with an accommodation space 169 which is open to the front and back. The accommodation space 169 accommodates the piezoelectric vibrator 161 fixed to the fixed substrate 170.

The nozzle plate 166 is a thin plate member having a large number of nozzle openings 165 formed along the sub-scanning direction. The nozzle openings 165 are opened at a predetermined pitch corresponding to the dot formation density. The vibrating plate 167 is a plate-shaped member including an island portion 171 as a thick wall portion with which the piezoelectric vibrator 161 abuts, and a thin wall portion 172 that is provided so as to surround the periphery of the island portion 171 and has elasticity. .

In the island portion 171, one island portion 171 corresponds to one nozzle opening 165,
Many are provided at a predetermined pitch.

The flow path forming plate 168 is provided with an opening for forming a pressure chamber 173, a common ink chamber 174, and an ink supply port 175 that connects these pressure chamber 173 and the common ink chamber 174. There is.

The nozzle plate 166 is arranged on the front surface of the flow path forming plate 168, the vibration plate 167 is arranged on the rear surface side, and the flow path forming plate 168 is sandwiched by the nozzle plate 166 and the vibration plate 167. In this state, the flow path unit 164 is formed integrally by adhesion or the like.

In this flow path unit 164, a pressure chamber 173 is formed on the back side of the nozzle opening 165, and the island portion 171 of the diaphragm 167 is located on the back side of this pressure chamber 173. In addition, the pressure chamber 173 and the common ink chamber 17
4 is in communication with the ink supply port 175.

The tip of the piezoelectric vibrator 161 is brought into contact with the island portion 171 from the back side, and the piezoelectric vibrator 161 is fixed to the base 163 in this contact state. In addition, through the flexible cable, to the piezoelectric vibrator 161,
Drive signal (COM) and print data (SI) which will be described in detail later
Etc. are supplied.

The piezoelectric vibrator 161 in the longitudinal vibration mode has a characteristic that it contracts in the direction orthogonal to the electric field when charged and expands in the direction orthogonal to the electric field when discharged. Therefore,
In the recording head 162, the piezoelectric vibrator 161 contracts backward by being charged, and the island portion 171 is pulled back by the contraction, and the contracted pressure chamber 173 expands. With this expansion, the common ink chamber 17
The ink of No. 4 passes through the ink supply port 175 and the pressure chamber 173.
Flows in. On the other hand, by discharging, the piezoelectric vibrator 1
61 extends forward, and is formed by the elastic plate island portion 17
1 is pushed forward and the pressure chamber 173 contracts. With this contraction, the ink pressure in the pressure chamber 173 increases.

In this way, in this recording head 162,
Voltage level due to charge / discharge of the piezoelectric vibrator 161 and pressure chamber 1
The relationship between expansion and contraction of 73 is opposite to that of the recording head 12 described above. Therefore, when the recording head 162 is used, a drive signal and a drive waveform in which the positive and negative of the voltage are reversed with respect to the intermediate potential as the drive signal described above are used. That is, in the recording head 162, the pressure chamber 17
Ink is filled in 3 by lowering the voltage. Similarly, ink droplets are ejected by increasing the voltage.

Then, the recording head 1 of this longitudinal vibration mode is used.
Even when 62 is used, the same effect as that of the above embodiment can be obtained.

[0079]

As described above, according to the present invention, the carriage mechanism is controlled so that the scanning speed of the carriage is higher in the high speed mode than in the normal mode, and in the high speed mode as compared with the normal mode. Controlling the drive signal generating means to shorten the drive cycle, and
When the ambient temperature is lower than the predetermined temperature in the high speed mode, the drive signal generating means is controlled to discharge the liquid having a waveform such that the amount of liquid sucked into the pressure chamber prior to the liquid droplet discharge becomes larger than that in the normal time. Since the drive signal capable of generating the pulse is generated, in the high speed mode, it is possible to perform the printing at a higher speed than in the normal mode while ensuring the ejection stability of the droplets.

[Brief description of drawings]

FIG. 1 is a perspective view showing a schematic configuration of an ink jet recording apparatus according to an embodiment of a liquid ejecting apparatus of the invention.

FIG. 2 is another perspective view showing a schematic configuration of an ink jet recording apparatus according to an embodiment of the liquid ejecting apparatus of the invention.

FIG. 3 is a cross-sectional view showing the structure of a recording head of the inkjet recording apparatus shown in FIGS. 1 and 2.

FIG. 4 is a functional block diagram of the inkjet recording apparatus shown in FIGS. 1 and 2.

5 is a block diagram showing a main part of a drive signal generation circuit of the inkjet recording apparatus shown in FIGS. 1 and 2. FIG.

FIG. 6 is a diagram showing drive signals used in the ink jet recording apparatus shown in FIGS. 1 and 2, (a) showing a drive signal when the environmental temperature is 25 ° C., and (b). Indicates a drive signal when the environmental temperature is 15 ° C.

FIG. 7 is a sectional view showing the structure of another recording head applicable to the present invention.

[Explanation of symbols]

12,162 recording head 47,165 Nozzle opening 25,161 Piezoelectric vibrator 31,173 Pressure chamber 32 actuator unit 33,174 Common ink chamber 34,164 Channel unit 37,167 Vibration plate 42,166 Nozzle plate 71 Electric drive system for recording head 72 shift register 73 Latch circuit 74 level shifter 75 switch 80 stepping motor 82 Control unit 83 Drive signal generation circuit (drive signal generation means)

Claims (12)

[Claims] 1. A pressure fluctuation is generated in a liquid in the pressure chamber by applying a discharge pulse to a pressure generating element provided corresponding to a pressure chamber communicating with the nozzle opening, and droplets are ejected from the nozzle opening. A recording head for discharging, a carriage having the recording head mounted thereon, a carriage mechanism for scanning the recording head together with the carriage in the main scanning direction, and a plurality of liquid droplets per pixel for discharging. Drive signal generating means for generating a drive signal capable of generating a plurality of the ejection pulses per one drive cycle, and one or a plurality of the ejection pulses are generated by selecting a part or all of the drive signals from the drive signals. The drive signal is generated in response to the switching operation between the pulse generating means and the normal mode for printing at the normal speed and the high speed mode for printing at a speed faster than the normal speed. And a control means for controlling the carriage mechanism, wherein the control means controls the carriage mechanism so that the scanning speed of the carriage is higher in the high speed mode than in the normal mode, In the high speed mode, the drive signal generating means is controlled so that the drive cycle becomes shorter than in the normal mode, and in the high speed mode, when the environmental temperature is lower than a predetermined temperature, the drive signal generation is performed. The means is controlled to generate the drive signal capable of generating the ejection pulse having a waveform such that the amount of liquid sucked into the pressure chamber prior to droplet ejection becomes larger than that in the normal time. Liquid ejector. 2. The control means further controls the drive signal generating means in the high speed mode so as to generate the drive signal in which the number of droplets ejected per pixel is smaller than that in the normal mode. The liquid ejecting apparatus according to claim 1, which is characterized in that. 3. The liquid ejecting apparatus according to claim 1, wherein the control means sets the allowable range of the environmental temperature in the high speed mode to be narrower than that in the normal mode. 4. The allowable range of the ambient temperature in the normal mode is about 10 ° C. to about 43 ° C., and the allowable range of the ambient temperature in the high speed mode is about 15 ° C. to about 35 ° C.
The liquid ejecting apparatus according to claim 3, wherein 5. The liquid ejecting apparatus according to claim 1, wherein the pressure generating element is constituted by a flexural vibration mode piezoelectric vibrator. 6. The pressure generating element is constituted by a piezoelectric vibrator of a longitudinal vibration mode.
5. The liquid ejecting apparatus according to any one of items 4 to 4. 7. A pressure fluctuation is generated in the liquid in the pressure chamber by applying a discharge pulse to a pressure generating element provided corresponding to the pressure chamber communicating with the nozzle opening, so that droplets are ejected from the nozzle opening. In order to discharge a plurality of droplets per pixel, a recording head for discharging, a carriage on which the recording head is mounted, and a carriage mechanism for scanning the recording head together with the carriage in the main scanning direction. Drive signal generating means for generating a drive signal capable of generating a plurality of ejection pulses per one drive cycle, and one or a plurality of ejection pulses are generated by selecting a part or all of the drive signals from the drive signals. The drive signal is generated in response to the switching operation between the pulse generation means and the normal mode for printing at the normal speed and the high speed mode for printing at a speed faster than the normal speed. A control method for a liquid ejecting apparatus, comprising: a step for controlling the carriage mechanism; and a control means for controlling the carriage mechanism, wherein the carriage mechanism is controlled so that the scanning speed of the carriage is higher in the high-speed mode than in the normal mode. At the same time, the drive signal generating means is controlled so that the drive cycle is shorter in the high speed mode than in the normal mode, and when the environmental temperature is lower than a predetermined temperature in the high speed mode, the drive is performed. The signal generation means is controlled to generate the drive signal capable of generating the ejection pulse having a waveform such that the amount of liquid sucked into the pressure chamber prior to droplet ejection becomes larger than in the normal state. A method for controlling a liquid ejecting apparatus. 8. The drive signal generating means is controlled so as to generate the drive signal in which the number of droplets ejected per pixel is smaller in the high speed mode than in the normal mode. Control method of the liquid ejecting apparatus. 9. The method of controlling a liquid ejecting apparatus according to claim 7, wherein the allowable range of the environmental temperature is set to be narrower in the high speed mode than in the normal mode. 10. The allowable range of the ambient temperature in the normal mode is about 10 ° C. to about 43 ° C., and the allowable range of the ambient temperature in the high speed mode is about 15 ° C. to about 35 ° C.
10. The method for controlling a liquid ejecting apparatus according to claim 9, wherein the temperature is C. 11. The method of controlling a liquid ejecting apparatus according to claim 7, wherein the pressure generating element is formed of a flexural vibration mode piezoelectric vibrator. 12. The method of controlling a liquid ejecting apparatus according to claim 7, wherein the pressure generating element is constituted by a longitudinal vibration mode piezoelectric vibrator.